[PATCH v6 4/5] selftests/breakpoints: extend riscv test for ptrace hw break/watchpoints

[Himanshu Chauhan]

Cover the new ptrace-based hardware breakpoint/watchpoint support
added for riscv: exercise the PTRACE_GETREGSET/SETREGSET regset path
as well as the raw PTRACE_GETHBPREGS/SETHBPREGS interface, alongside
the existing perf_event-based tests.

Also drop a leftover #if 0 block duplicating the HWDEBUG_* control
field macros already defined in uapi/asm/ptrace.h.

Signed-off-by: Himanshu Chauhan <himanshu.chauhan@xxxxxxxxxxxxxxxx>
---
 .../breakpoints/breakpoint_test_riscv.c       | 590 +++++++++++++++++-
 1 file changed, 568 insertions(+), 22 deletions(-)

diff --git a/tools/testing/selftests/breakpoints/breakpoint_test_riscv.c b/tools/testing/selftests/breakpoints/breakpoint_test_riscv.c
index 0649940b709e..ee6641531fa7 100644
--- a/tools/testing/selftests/breakpoints/breakpoint_test_riscv.c
+++ b/tools/testing/selftests/breakpoints/breakpoint_test_riscv.c
@@ -9,6 +9,7 @@
 #include <linux/perf_event.h>    /* Definition of PERF_* constants */
 #include <linux/hw_breakpoint.h> /* Definition of HW_* constants */
 #include <sys/syscall.h>         /* Definition of SYS_* constants */
+#include <asm/ptrace.h>
 #include <unistd.h>
 #include <stdbool.h>
 #include <stdio.h>
@@ -18,18 +19,572 @@
 #include <fcntl.h>
 #include <signal.h>
 #include <sys/mman.h>
+#include <sys/ptrace.h>
+#include <sys/wait.h>
 #include <string.h>
 #include <semaphore.h>
 #include <errno.h>
+#include <stdint.h>
+#include <stddef.h>
+#include <linux/elf.h>
 
 #ifndef noinline
 #define noinline __attribute__((noinline))
 #endif
 
+#include "kselftest.h"
+
+static int test_func_sink;
+
+/*
+ * Keep a real instruction address for HW execute breakpoints: prevent inlining
+ * and force a visible side effect so the function can't be optimized away.
+ */
+static noinline void test_func(void)
+{
+	test_func_sink++;
+	__asm__ __volatile__("" : : "g" (test_func_sink));
+}
+
+/*
+ * BREAKPOINT TEST USING PTRACE
+ */
+static int do_wp_child(void *addr, size_t size)
+{
+	if (ptrace(PTRACE_TRACEME, 0, NULL, NULL) != 0) {
+		ksft_print_msg(
+			       "ptrace(PTRACE_TRACEME) failed: %s\n",
+			       strerror(errno));
+		_exit(1);
+	}
+
+	if (raise(SIGSTOP) != 0) {
+		ksft_print_msg(
+			       "raise(SIGSTOP) failed: %s\n", strerror(errno));
+		_exit(1);
+	}
+
+	sleep(1);
+	switch (size) {
+	case 1:
+		*(uint8_t *)addr = 47;
+		break;
+	case 2:
+		*(uint16_t *)addr = 47;
+		break;
+	case 4:
+		*(uint32_t *)addr = 47;
+		break;
+	case 8:
+		*(uint64_t *)addr = 47;
+		break;
+	default:
+		ksft_print_msg("Unknown watchpoint access size %u\n", size);
+		break;
+	}
+
+	_exit(0);
+}
+
+static int do_bp_child(void (*bp_func)(void))
+{
+	if (ptrace(PTRACE_TRACEME, 0, NULL, NULL) != 0) {
+		ksft_print_msg(
+			       "ptrace(PTRACE_TRACEME) failed: %s\n",
+			       strerror(errno));
+		_exit(1);
+	}
+
+	if (raise(SIGSTOP) != 0) {
+		ksft_print_msg(
+			       "raise(SIGSTOP) failed: %s\n", strerror(errno));
+		_exit(1);
+	}
+
+	bp_func();
+}
+
+unsigned long var;
+
+static bool set_watchpoint(pid_t pid, int size)
+{
+	uint8_t *addr = (uint8_t *)&var;
+	unsigned int control = 0;
+	struct user_hwdebug_state dreg_state;
+	struct iovec iov;
+
+	/* Write watchpoint */
+	control = (HW_BREAKPOINT_W << 14) & ((0x7 << 14));
+	control |= (HW_BREAKPOINT_LEN_8 << 4) & ((0x1f << 4));
+	memset(&dreg_state, 0, sizeof(dreg_state));
+	dreg_state.dbg_regs[0].addr = (uintptr_t)(addr);
+	dreg_state.dbg_regs[0].control = control;
+	iov.iov_base = &dreg_state;
+	iov.iov_len = offsetof(struct user_hwdebug_state, dbg_regs) +
+				sizeof(dreg_state.dbg_regs[0]);
+
+	if (ptrace(PTRACE_SETREGSET, pid, NT_RISCV_HW_WATCH, &iov) == 0) {
+		memset(&iov, 0, sizeof(iov));
+		memset(&dreg_state, 0, sizeof(dreg_state));
+
+		iov.iov_base = &dreg_state;
+		iov.iov_len = offsetof(struct user_hwdebug_state, dbg_regs) +
+			sizeof(dreg_state.dbg_regs[0]);
+
+		if (ptrace(PTRACE_GETREGSET, pid, NT_RISCV_HW_WATCH, &iov) == 0) {
+			ksft_print_msg(
+				       "ptrace(PTRACE_GETREGSET): Number of watchpoints: %u\n", dreg_state.info);
+			ksft_print_msg(
+				       "ptrace(PTRACE_GETREGSet): addr: 0x%lx control: 0x%x\n", dreg_state.dbg_regs[0].addr, dreg_state.dbg_regs[0].control);
+		} else {
+			ksft_print_msg(
+				       "ptrace(PTRACE_GETREGSET): Failed\n");
+			return false;
+		}
+
+		return true;
+	}
+
+	if (errno == EIO)
+		ksft_print_msg(
+			       "ptrace(PTRACE_SETREGSET, NT_RISCV_HW_WATCH) not supported on this hardware: %s\n",
+			       strerror(errno));
+	else
+		ksft_print_msg(
+			       "ptrace(PTRACE_SETREGSET, NT_RISCV_HW_WATCH) failed: %s\n",
+			       strerror(errno));
+	return false;
+}
+
+static bool set_breakpoint(pid_t pid, void (*bp_func)(void))
+{
+	struct user_hwdebug_state dreg_state;
+	struct iovec iov;
+	unsigned int control = 0;
+
+	control = (HW_BREAKPOINT_X << 14) & ((0x7 << 14));
+	control |= (HW_BREAKPOINT_LEN_8 << 4) & ((0x1f << 4));
+	memset(&dreg_state, 0, sizeof(dreg_state));
+	dreg_state.dbg_regs[0].addr = (uintptr_t)bp_func;
+	dreg_state.dbg_regs[0].control = control;
+	iov.iov_base = &dreg_state;
+	iov.iov_len = offsetof(struct user_hwdebug_state, dbg_regs) + sizeof(dreg_state.dbg_regs[0]);
+
+	if (ptrace(PTRACE_SETREGSET, pid, NT_RISCV_HW_BREAK, &iov) == 0)
+		return true;
+
+	if (errno == EIO)
+		ksft_print_msg(
+			       "ptrace(PTRACE_SETREGSET, NT_RISCV_HW_BREAK) not supported on this hardware: %s\n", strerror(errno));
+	else
+		ksft_print_msg(
+			       "ptrace(PTRACE_SETREGSET, NT_RISCV_HW_BREAK) failed: %s\n", strerror(errno));
+
+	return false;
+}
+
+static int run_ptrace_wp_test(void)
+{
+	pid_t pid = fork();
+	pid_t wpid;
+	siginfo_t siginfo;
+	int status;
+
+	if (pid == 0)
+		do_wp_child(&var, 8);
+
+	wpid = waitpid(pid, &status, __WALL);
+	if (wpid != pid) {
+		ksft_print_msg(
+			"waitpid() failed: %s\n", strerror(errno));
+		return false;
+	}
+	if (!WIFSTOPPED(status)) {
+		ksft_print_msg(
+			"child did not stop: %s\n", strerror(errno));
+		return false;
+	}
+	if (WSTOPSIG(status) != SIGSTOP) {
+		ksft_print_msg("child did not stop with SIGSTOP\n");
+		return false;
+	}
+
+	if (!set_watchpoint(pid, 8))
+		return false;
+
+	if (ptrace(PTRACE_CONT, pid, NULL, NULL) < 0) {
+		ksft_print_msg(
+			"ptrace(PTRACE_CONT) failed: %s\n",
+			strerror(errno));
+		return false;
+	}
+
+	alarm(3);
+	wpid = waitpid(pid, &status, __WALL);
+	if (wpid != pid) {
+		ksft_print_msg(
+			"waitpid() failed: %s\n", strerror(errno));
+		return false;
+	}
+	alarm(0);
+	if (WIFEXITED(status)) {
+		ksft_print_msg("child exited prematurely\n");
+		return false;
+	}
+	if (!WIFSTOPPED(status)) {
+		ksft_print_msg("child did not stop\n");
+		return false;
+	}
+	if (WSTOPSIG(status) != SIGTRAP) {
+		ksft_print_msg("child did not stop with SIGTRAP\n");
+		return false;
+	}
+	if (ptrace(PTRACE_GETSIGINFO, pid, NULL, &siginfo) != 0) {
+		ksft_print_msg(
+			"ptrace(PTRACE_GETSIGINFO): %s\n",
+			strerror(errno));
+		return false;
+	}
+	if (siginfo.si_code != TRAP_HWBKPT) {
+		ksft_print_msg(
+			"Unexpected si_code %d\n", siginfo.si_code);
+		return false;
+	}
+
+	kill(pid, SIGKILL);
+	wpid = waitpid(pid, &status, 0);
+	if (wpid != pid) {
+		ksft_print_msg(
+			"waitpid() failed: %s\n", strerror(errno));
+		return false;
+	}
+
+	ksft_print_msg("[ptrace]: Watchpoint test passed!\n");
+
+	return true;
+}
+
+static int run_ptrace_bp_test(void)
+{
+	pid_t pid = fork();
+	pid_t wpid;
+	siginfo_t siginfo;
+	int status;
+
+	if (pid == 0)
+		do_bp_child(test_func);
+
+	wpid = waitpid(pid, &status, __WALL);
+	if (wpid != pid) {
+		ksft_print_msg(
+			"waitpid() failed: %s\n", strerror(errno));
+		return false;
+	}
+	if (!WIFSTOPPED(status)) {
+		ksft_print_msg(
+			"child did not stop: %s\n", strerror(errno));
+		return false;
+	}
+	if (WSTOPSIG(status) != SIGSTOP) {
+		ksft_print_msg("child did not stop with SIGSTOP\n");
+		return false;
+	}
+
+	if (!set_breakpoint(pid, test_func))
+		return false;
+
+	if (ptrace(PTRACE_CONT, pid, NULL, NULL) < 0) {
+		ksft_print_msg(
+			"ptrace(PTRACE_CONT) failed: %s\n",
+			strerror(errno));
+		return false;
+	}
+
+	alarm(3);
+	wpid = waitpid(pid, &status, __WALL);
+	if (wpid != pid) {
+		ksft_print_msg(
+			"waitpid() failed: %s\n", strerror(errno));
+		return false;
+	}
+	alarm(0);
+	if (WIFEXITED(status)) {
+		ksft_print_msg("child exited prematurely\n");
+		return false;
+	}
+	if (!WIFSTOPPED(status)) {
+		ksft_print_msg("child did not stop\n");
+		return false;
+	}
+	if (WSTOPSIG(status) != SIGTRAP) {
+		ksft_print_msg("child did not stop with SIGTRAP\n");
+		return false;
+	}
+	if (ptrace(PTRACE_GETSIGINFO, pid, NULL, &siginfo) != 0) {
+		ksft_print_msg(
+			"ptrace(PTRACE_GETSIGINFO): %s\n",
+			strerror(errno));
+		return false;
+	}
+	if (siginfo.si_code != TRAP_HWBKPT) {
+		ksft_print_msg(
+			"Unexpected si_code %d\n", siginfo.si_code);
+		return false;
+	}
+
+	kill(pid, SIGKILL);
+	wpid = waitpid(pid, &status, 0);
+	if (wpid != pid) {
+		ksft_print_msg(
+			"waitpid() failed: %s\n", strerror(errno));
+		return false;
+	}
+
+	ksft_print_msg("[ptrace]: Breakpoint test passed!\n");
+
+	return true;
+}
+
+/*
+ * BREAKPOINT TEST USING PTRACE_SETHBPREGS / PTRACE_GETHBPREGS
+ */
+static bool set_hbpregs_watchpoint(pid_t pid)
+{
+	struct __riscv_hwdebug_state state;
+
+	memset(&state, 0, sizeof(state));
+	state.addr = (unsigned long)&var;
+	state.len  = HW_BREAKPOINT_LEN_8;
+	state.type = HW_BREAKPOINT_W;
+	state.ctrl = 0; /* enabled */
+
+	if (ptrace(PTRACE_SETHBPREGS, pid, 0, &state) != 0) {
+		ksft_print_msg(
+			"ptrace(PTRACE_SETHBPREGS) failed: %s\n",
+			strerror(errno));
+		return false;
+	}
+
+	/* Read back and verify */
+	memset(&state, 0, sizeof(state));
+	if (ptrace(PTRACE_GETHBPREGS, pid, 0, &state) != 0) {
+		ksft_print_msg(
+			"ptrace(PTRACE_GETHBPREGS) failed: %s\n",
+			strerror(errno));
+		return false;
+	}
+
+	ksft_print_msg(
+		"[hbpregs] watchpoint readback: addr=0x%lx type=%lu len=%lu ctrl=%lu\n",
+		state.addr, state.type, state.len, state.ctrl);
+
+	return true;
+}
+
+static bool set_hbpregs_breakpoint(pid_t pid, void (*bp_func)(void))
+{
+	struct __riscv_hwdebug_state state;
+
+	memset(&state, 0, sizeof(state));
+	state.addr = (unsigned long)bp_func;
+	state.len  = HW_BREAKPOINT_LEN_4;
+	state.type = HW_BREAKPOINT_X;
+	state.ctrl = 0; /* enabled */
+
+	if (ptrace(PTRACE_SETHBPREGS, pid, 0, &state) != 0) {
+		ksft_print_msg(
+			"ptrace(PTRACE_SETHBPREGS) failed: %s\n",
+			strerror(errno));
+		return false;
+	}
+
+	/* Read back and verify */
+	memset(&state, 0, sizeof(state));
+	if (ptrace(PTRACE_GETHBPREGS, pid, 0, &state) != 0) {
+		ksft_print_msg(
+			"ptrace(PTRACE_GETHBPREGS) failed: %s\n",
+			strerror(errno));
+		return false;
+	}
+
+	ksft_print_msg(
+		"[hbpregs] breakpoint readback: addr=0x%lx type=%lu len=%lu ctrl=%lu\n",
+		state.addr, state.type, state.len, state.ctrl);
+
+	return true;
+}
+
+static int run_hbpregs_wp_test(void)
+{
+	pid_t pid = fork();
+	pid_t wpid;
+	siginfo_t siginfo;
+	int status;
+
+	if (pid == 0)
+		do_wp_child(&var, 8);
+
+	wpid = waitpid(pid, &status, __WALL);
+	if (wpid != pid) {
+		ksft_print_msg("waitpid() failed: %s\n", strerror(errno));
+		return false;
+	}
+	if (!WIFSTOPPED(status)) {
+		ksft_print_msg("child did not stop: %s\n", strerror(errno));
+		return false;
+	}
+	if (WSTOPSIG(status) != SIGSTOP) {
+		ksft_print_msg("child did not stop with SIGSTOP\n");
+		return false;
+	}
+
+	if (!set_hbpregs_watchpoint(pid))
+		return false;
+
+	if (ptrace(PTRACE_CONT, pid, NULL, NULL) < 0) {
+		ksft_print_msg("ptrace(PTRACE_CONT) failed: %s\n",
+			strerror(errno));
+		return false;
+	}
+
+	alarm(3);
+	wpid = waitpid(pid, &status, __WALL);
+	if (wpid != pid) {
+		ksft_print_msg("waitpid() failed: %s\n", strerror(errno));
+		return false;
+	}
+	alarm(0);
+	if (WIFEXITED(status)) {
+		ksft_print_msg("child exited prematurely\n");
+		return false;
+	}
+	if (!WIFSTOPPED(status)) {
+		ksft_print_msg("child did not stop\n");
+		return false;
+	}
+	if (WSTOPSIG(status) != SIGTRAP) {
+		ksft_print_msg("child did not stop with SIGTRAP\n");
+		return false;
+	}
+	if (ptrace(PTRACE_GETSIGINFO, pid, NULL, &siginfo) != 0) {
+		ksft_print_msg("ptrace(PTRACE_GETSIGINFO): %s\n",
+			strerror(errno));
+		return false;
+	}
+	if (siginfo.si_code != TRAP_HWBKPT) {
+		ksft_print_msg("Unexpected si_code %d\n", siginfo.si_code);
+		return false;
+	}
+
+	kill(pid, SIGKILL);
+	wpid = waitpid(pid, &status, 0);
+	if (wpid != pid) {
+		ksft_print_msg("waitpid() failed: %s\n", strerror(errno));
+		return false;
+	}
+
+	ksft_print_msg("[hbpregs]: Watchpoint test passed!\n");
+	return true;
+}
+
+static int run_hbpregs_bp_test(void)
+{
+	pid_t pid = fork();
+	pid_t wpid;
+	siginfo_t siginfo;
+	int status;
+
+	if (pid == 0)
+		do_bp_child(test_func);
+
+	wpid = waitpid(pid, &status, __WALL);
+	if (wpid != pid) {
+		ksft_print_msg("waitpid() failed: %s\n", strerror(errno));
+		return false;
+	}
+	if (!WIFSTOPPED(status)) {
+		ksft_print_msg("child did not stop: %s\n", strerror(errno));
+		return false;
+	}
+	if (WSTOPSIG(status) != SIGSTOP) {
+		ksft_print_msg("child did not stop with SIGSTOP\n");
+		return false;
+	}
+
+	if (!set_hbpregs_breakpoint(pid, test_func))
+		return false;
+
+	if (ptrace(PTRACE_CONT, pid, NULL, NULL) < 0) {
+		ksft_print_msg("ptrace(PTRACE_CONT) failed: %s\n",
+			strerror(errno));
+		return false;
+	}
+
+	alarm(3);
+	wpid = waitpid(pid, &status, __WALL);
+	if (wpid != pid) {
+		ksft_print_msg("waitpid() failed: %s\n", strerror(errno));
+		return false;
+	}
+	alarm(0);
+	if (WIFEXITED(status)) {
+		ksft_print_msg("child exited prematurely\n");
+		return false;
+	}
+	if (!WIFSTOPPED(status)) {
+		ksft_print_msg("child did not stop\n");
+		return false;
+	}
+	if (WSTOPSIG(status) != SIGTRAP) {
+		ksft_print_msg("child did not stop with SIGTRAP\n");
+		return false;
+	}
+	if (ptrace(PTRACE_GETSIGINFO, pid, NULL, &siginfo) != 0) {
+		ksft_print_msg("ptrace(PTRACE_GETSIGINFO): %s\n",
+			strerror(errno));
+		return false;
+	}
+	if (siginfo.si_code != TRAP_HWBKPT) {
+		ksft_print_msg("Unexpected si_code %d\n", siginfo.si_code);
+		return false;
+	}
+
+	kill(pid, SIGKILL);
+	wpid = waitpid(pid, &status, 0);
+	if (wpid != pid) {
+		ksft_print_msg("waitpid() failed: %s\n", strerror(errno));
+		return false;
+	}
+
+	ksft_print_msg("[hbpregs]: Breakpoint test passed!\n");
+	return true;
+}
+
+static void run_hbpregs_tests(void)
+{
+	run_hbpregs_bp_test();
+	run_hbpregs_wp_test();
+}
+
+/*
+ * BREAKPOINT TEST USING PTRACE_SETHBPREGS / PTRACE_GETHBPREGS - END
+ */
+static void run_ptrace_tests(void)
+{
+	run_ptrace_bp_test();
+	run_ptrace_wp_test();
+}
+
+/*
+ * BREAKPOINT TEST USING PTRACE - END
+ */
+
+/*
+ * BREAKPOINT TEST USING perf events
+ */
 static int gfd;
 sem_t ib_mtx, wp_mtx;
 static int bp_triggered, wp_triggered;
-static int test_func_sink;
 static const int wait_timeout_sec = 5;
 
 int setup_bp(bool is_x, void *addr, int sig)
@@ -56,7 +611,7 @@ int setup_bp(bool is_x, void *addr, int sig)
 
 	fd = syscall(SYS_perf_event_open, &pe, 0, -1, -1, 0);
 	if (fd < 0) {
-		printf("Failed to open event: %llx\n", pe.config);
+		ksft_print_msg("Failed to open event: %llx\n", pe.config);
 		return -1;
 	}
 
@@ -75,11 +630,10 @@ static void sig_handler_bp(int signum, siginfo_t *oh, void *uc)
 
 	bp_triggered++;
 
-	printf("Breakpoint triggered!\n");
 	ioctl(gfd, PERF_EVENT_IOC_DISABLE, 0);
 	ret = sem_post(&ib_mtx);
 	if (ret) {
-		printf("Failed to report BP success\n");
+		ksft_print_msg("Failed to report BP success\n");
 		return;
 	}
 }
@@ -88,28 +642,17 @@ static void sig_handler_wp(int signum, siginfo_t *oh, void *uc)
 {
 	int ret;
 
-	printf("Watchpoint triggered!\n");
 	ioctl(gfd, PERF_EVENT_IOC_DISABLE, 0);
 	wp_triggered++;
 
 	ret = sem_post(&wp_mtx);
 
 	if (ret) {
-		printf("Failed to report WP success\n");
+		ksft_print_msg("Failed to report WP success\n");
 		return;
 	}
 }
 
-/*
- * Keep a real instruction address for HW execute breakpoints: prevent inlining
- * and force a visible side effect so the function can't be optimized away.
- */
-static noinline void test_func(void)
-{
-	test_func_sink++;
-	__asm__ __volatile__("" : : "g" (test_func_sink));
-}
-
 static int trigger_bp(void)
 {
 	struct sigaction sa;
@@ -119,14 +662,14 @@ static int trigger_bp(void)
 	sa.sa_flags = SA_SIGINFO;
 
 	if (sigaction(SIGIO, &sa, NULL) < 0) {
-		printf("Failed to setup signal handler\n");
+		ksft_print_msg("Failed to setup signal handler\n");
 		return -1;
 	}
 
 	gfd = setup_bp(1, test_func, SIGIO);
 
 	if (gfd < 0) {
-		printf("Failed to setup breakpoint.\n");
+		ksft_print_msg("Failed to setup breakpoint.\n");
 		return -1;
 	}
 
@@ -151,14 +694,14 @@ static int trigger_wp(void)
 	sa.sa_flags = SA_SIGINFO;
 
 	if (sigaction(SIGUSR1, &sa, NULL) < 0) {
-		printf("Failed to setup signal handler\n");
+		ksft_print_msg("Failed to setup signal handler\n");
 		return -1;
 	}
 
 	gfd = setup_bp(0, &test_data, SIGUSR1);
 
 	if (gfd < 0) {
-		printf("Failed to setup watchpoint\n");
+		ksft_print_msg("Failed to setup watchpoint\n");
 		return -1;
 	}
 
@@ -204,7 +747,7 @@ int main(int argc, char *argv[])
 		return -1;
 
 	if (bp_triggered)
-		printf("Breakpoint test passed!\n");
+		ksft_print_msg("[perf_event]: Breakpoint test passed!\n");
 
 	sem_init(&wp_mtx, 0, 0);
 	if (trigger_wp() < 0)
@@ -213,7 +756,10 @@ int main(int argc, char *argv[])
 		return -1;
 
 	if (wp_triggered)
-		printf("Watchpoint test passed!\n");
+		ksft_print_msg("[perf_event]: Watchpoint test passed!\n");
+
+	run_ptrace_tests();
+	run_hbpregs_tests();
 
 	return 0;
 }
-- 
2.43.0